Flutter TextField获取选定文本

import 'package:flutter/material.dart';

class MyTextField extends StatefulWidget {
  @override
  _MyTextFieldState createState() => _MyTextFieldState();
}

class _MyTextFieldState extends State<MyTextField> {
  TextEditingController _controller = TextEditingController();
  String _selectedText = '';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('TextField Demo'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            TextField(
              controller: _controller,
            ),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: () {
                setState(() {
                  _selectedText = _controller.selection.textInside(_controller.text);
                });
              },
              child: Text('Get Selected Text'),
            ),
            SizedBox(height: 20),
            Text('Selected Text: $_selectedText'),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: MyTextField(),
  ));
}